Sensor chip, electronic apparatus, and distance measurement apparatus

ABSTRACT

A sensor chip according to an embodiment of the present disclosure includes a pixel. The pixel includes a photoelectric converter, a light reflector, and a light collector. The photoelectric converter includes a light entering surface which light enters and a multiplication region in which avalanche multiplication of carriers is caused by a high electric-field region. The light reflector is provided to oppose a surface, of the photoelectric converter, on an opposite side to the light entering surface. The light collector is provided between the photoelectric converter and the light reflector.

TECHNICAL FIELD

The present disclosure relates to a sensor chip having, for example, anavalanche photodiode, an electronic apparatus including the same, and adistant measurement apparatus.

BACKGROUND ART

An avalanche photodiode (APD; Avalanche Photodiode) is a photodiode inwhich a high electric-field region is provided in a depletion layer thatspreads as a result of application of a predetermined reverse voltage toa p-n junction. Formation of a high electric-field region allows foroccurrence of avalanche multiplication (avalanche breakdown) whichinvolves a repetitive process in which carriers (electrons) generated bya photoelectric effect are accelerated by an electric field and causeimpact ionization.

The APD can be driven in a linear mode in which it is driven near abreakdown voltage and can be also driven in a Geiger mode in which it isdriven with a voltage higher than the breakdown voltage. The APD of theGeiger mode is also referred to as a single photon avalanche diode(SPAD; Single Photon Avalanche Diode), and is able to detect a singlephoton entering the photodiode.

PTL 1 discloses a sensor chip in which pixels including avalanchephotodiodes are disposed in an array.

CITATION LIST Patent Literature

-   PTL 1: Japanese Unexamined Patent Application Publication No.    2018-88488

SUMMARY OF THE INVENTION

Regarding a sensor including an SPAD, it is desired to improve PDE(Photon Detection Efficiency).

It is desirable to provide a sensor chip that includes an SPAD andallows for improvement in PDE, an electronic apparatus that includessuch a sensor chip, and a distance measurement apparatus that includessuch a sensor chip.

A sensor chip according to an embodiment of the present disclosureincludes a pixel including a photoelectric converter, a light reflector,and a light collector. The photoelectric converter includes a lightentering surface which light enters and a multiplication region in whichavalanche multiplication of carriers is caused by a high electric-fieldregion. The light reflector is provided to oppose a surface, of thephotoelectric converter, on an opposite side to the light enteringsurface. The light collector is provided between the photoelectricconverter and the light reflector.

An electronic apparatus according to an embodiment of the presentdisclosure includes an optical system, a sensor chip, and a signalprocessing circuit, and includes, as the sensor chip, the sensor chipaccording to the embodiment of the present disclosure described above.

A distance measurement apparatus according to an embodiment of thepresent disclosure includes an optical system, a sensor chip, and asignal processing circuit that calculates a distance from an outputsignal of the sensor chip to a measurement target, and includes, as thesensor chip, the sensor chip according to the embodiment of the presentdisclosure described above.

In the sensor chip according to the embodiment of the presentdisclosure, the electronic apparatus according to the embodiment, andthe distance measurement apparatus according to the embodiment, thelight collector is provided between the photoelectric converter and thelight reflector to thereby collect the light passing through thephotoelectric converter toward the light reflector.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an example of a cross-sectionalconfiguration of a sensor chip according to an embodiment of the presentdisclosure.

FIG. 2 is a diagram illustrating an example of a planar configuration ofa diffractive lens of the sensor chip illustrated in FIG. 1.

FIG. 3 is a diagram illustrating an example of a cross-sectionalconfiguration of a sensor chip according to Modification A.

FIG. 4 is a diagram illustrating an example of a cross-sectionalconfiguration of a sensor chip according to Modification B.

FIG. 5 is a diagram illustrating an example of a cross-sectionalconfiguration of a sensor chip according to Modification C.

FIG. 6 is a diagram illustrating an example of a cross-sectionalconfiguration of a sensor chip according to Modification D.

FIG. 7 is a diagram illustrating an example of a cross-sectionalconfiguration of a sensor chip according to Modification E.

FIG. 8 is a diagram illustrating an example of a planar configuration ofa contact layer of the sensor chip illustrated in FIG. 7.

FIG. 9 is a diagram illustrating an example of a cross-sectionalconfiguration of a sensor chip according to Modification F.

FIG. 10 is a diagram illustrating an example of a cross-sectionalconfiguration of a sensor chip according to Modification G.

FIG. 11 is a diagram illustrating an example of a cross-sectionalconfiguration of a sensor chip according to Modification H.

FIG. 12 is a diagram illustrating an example of a cross-sectionalconfiguration of a sensor chip according to Modification I.

FIG. 13 is a diagram illustrating an example of a cross-sectionalconfiguration of a sensor chip according to Modification J.

FIG. 14 is a block diagram illustrating an example of a schematicconfiguration of an electronic apparatus that includes the sensor chipaccording to any of the embodiment and the modifications thereofdescribed above.

FIG. 15 is a block diagram depicting an example of schematicconfiguration of a vehicle control system.

FIG. 16 is a diagram of assistance in explaining an example ofinstallation positions of an outside-vehicle information detectingsection and an imaging section.

MODES FOR CARRYING OUT THE INVENTION

In the following, an embodiment of the present disclosure is describedin detail with reference to the drawings. Note that the description isgiven in the following order.

1. Embodiment (sensor chip) . . . FIGS. 1 and 2

An example in which a diffractive lens including a stacked body of aninsulating film and an electrically conductive film is provided betweenan SPAD and a light reflection film.

2. Modifications (sensor chip)

Modification A: An example in which the diffractive lens includes aninsulating film buried in a groove of a semiconductor substrate . . .FIG. 3

Modification B: An example in which the diffractive lens includes anelectrically conductive film or an insulating film . . . FIG. 4

Modification C: An example in which an inner lens is provided betweenthe SPAD and the light reflection film . . . FIG. 5

Modification D: An example in which the diffractive lens includes afirst wiring line . . . FIG. 6

Modification E: An example in which a contact layer is provided in eachfirst wiring line included in the diffractive lens . . . FIGS. 7 and 8

Modification F: An example in which a cathode of the SPAD is provided ata middle part of a pixel . . . FIG. 9

Modification G: An example in which the light reflection film isprovided on a second wiring line and opposes a portion, of the pixel,including the middle part of the pixel . . . FIG. 10

Modification H: An example in which the light reflection film isprovided on the first wiring line and opposes a portion, of the pixel,including the middle part of the pixel . . . FIG. 11

Modification I: An example in which a light entering surface not havingconcavities and convexities . . . FIG. 12

Modification J: An example in which no on-chip lens is provided . . .FIG. 13

3. Application Example: An example in which the sensor chip according toany of the embodiment and the modifications thereof described above isapplied to an electronic apparatus . . . FIG. 144. Practical Application Example: An example in which the sensor chipaccording to any of the embodiment and the modifications thereofdescribed above is applied to a mobile body . . . FIGS. 15 and 16

5. Other Modifications 1. EMBODIMENT Configuration Example

FIG. 1 illustrates an example of a cross-sectional configuration of asensor chip 1 according to an embodiment of the present disclosure. Thesensor chip 1 includes a pixel array in which two or more pixels P aredisposed in an array. The pixel P corresponds to one specific example ofa “pixel” of the present disclosure.

The pixels P each have a structure in which an SPAD 2 and a wiring layer26 are stacked. The wiring layer 26 includes a light reflection film LR,and a diffractive lens DL is provided between the SPAD 2 and the lightreflection film LR. This SPAD 2 corresponds to one specific example of a“photoelectric converter” of the present disclosure. The lightreflection film LR corresponds to one specific example of a “lightreflector” of the present disclosure. The diffractive lens DLcorresponds to one specific example of a “light collector” of thepresent disclosure.

The sensor chip 1 is a back-illuminated sensor chip that detects lightentering from a back surface of a semiconductor substrate 10. The SPAD 2is provided in the semiconductor substrate 10 and includes amultiplication region MR in which avalanche multiplication of carriers(electrons) is caused by a high electric-field region. The SPAD 2includes a light entering surface 10A. One surface of the semiconductorsubstrate 10 corresponds to the light entering surface 10A of the SPAD2. The light entering surface 10A is a surface obtained as a result ofpolishing the back surface of the semiconductor substrate 10. The lightentering surface 10A is also referred to as the back surface of thesemiconductor substrate 10. Further, the other surface (a surface on anopposite side to the light entering surface 10A) of the semiconductorsubstrate 10 is also referred to as a surface 10C of the semiconductorsubstrate 10. The light reflection film LR is provided to oppose thesurface 10C of the semiconductor substrate 10.

The semiconductor substrate 10 is provided with a pixel separationgroove 30 that separates adjacent pixels P. A pixel separation film TIis buried in the pixel separation groove 30. The pixel separation filmTI has, for example, a stacked structure of an insulating film 31 and alight-blocking metal film 32. The insulating film 31 includes a siliconoxide (SiO₂), a tantalum oxide (Ta₂O₅), a hafnium oxide (HfO₂), analuminum oxide (Al₂O₃), etc. The metal film 32 includes tungsten (W),aluminum (Al), etc. Further, a void V is provided inside the metal film32. Thus, the adjacent pixels P are electrically and optically separatedfrom each other. Note that the void V inside the metal film 32 does nothave to be provided.

The SPAD 2 provided in the semiconductor substrate 10 is described. Awell layer 11 is provided in a region, of the semiconductor substrate10, separated by the pixel separation film TI. Inside the well layer 11,a p-type semiconductor region 14 on the light entering surface 10A sideand an n-type semiconductor region 15 on the surface 10C side of thesemiconductor substrate 10 are provided in such a manner as to provide ap-n junction. A cathode 16 is provided in such a manner as to runthrough from the n-type semiconductor region 15 to the surface 10C sideof the semiconductor substrate 10. Further, a pinning layer 12 isprovided between a side surface of the well layer 11 and the pixelseparation film TI. The pinning layer 12 is a p-type semiconductorregion. An anode 13 is provided at an end of the pinning layer 12 on thesurface 10C side of the semiconductor substrate 10. The anode 13 is ap-type semiconductor region.

The semiconductor substrate 10 includes, for example, silicon (Si). Thewell layer 11 may be an n-type semiconductor region or a p-typesemiconductor region. The well layer 11 is preferably an n-type orp-type semiconductor region having a low concentration of about 1×10¹⁴atoms/cm⁻³ or less, for example. This makes it easier to deplete thewell layer 11, making it possible to improve PDE of the SPAD 2.

The p-type semiconductor region 14 is a p-type semiconductor region (p+)having a high impurity concentration. The n-type semiconductor region 15is an n-type semiconductor region (n+) having a high impurityconcentration.

The cathode 16 is an n-type semiconductor region (n++) having a highimpurity concentration. The cathode 16 is coupled to the n-typesemiconductor region 15 and is provided to be able to apply apredetermined bias to the n-type semiconductor region 15.

The pinning layer 12 is a p-type semiconductor region (p). The pinninglayer 12 is provided in such a manner as to surround the side surface ofthe well layer 11 along the pixel separation film TI. The pinning layer12 accumulates holes. The anode 13 is coupled to the pinning layer 12,and bias adjustment thereof is allowed to be performed from the anode13. This enhances the hole concentration of the pinning layer 12, makingthe pinning stronger. Accordingly, it is possible to suppress generationof a dark current generated at an interface between the pixel separationfilm TI and the well layer 11, for example. The pinning layer 12 mayhave, for example, a structure in which the p-type semiconductor region(p+) and the p-type semiconductor region (p) are stacked in this orderas viewed from the pixel separation film TI.

The anode 13 is a p-type semiconductor region (p++) having a highimpurity concentration. The anode 13 is coupled to the pinning layer 12and is provided to be able to apply a predetermined bias to the pinninglayer 12.

The SPAD 2 is configured in such a manner that application of apredetermined reverse voltage to the p-n junction caused by applicationof a high negative voltage to the anode 13 results in spreading of thedepletion layer from the p-n junction of the p-type semiconductor region14 and the n-type semiconductor region 15, thereby forming a highelectric-field region. When the high electric-field region is formed,the multiplication region MR that allows for avalanche multiplication ofcarriers is formed. Owing to the avalanche multiplication occurring inthe multiplication region MR, the SPAD 2 is able to multiply carriersgenerated by a single photon entering from the light entering surface10A and detect the multiplied carriers. The SPAD 2 is configured asdescribed above.

A second concave-convex section 10D is provided on the surface 10C (thesurface on the opposite side to the light entering surface 10A) of thesemiconductor substrate 10 (a first concave-convex section 10B will bedescribed later). The second concave-convex section 10D includes astacked body of an insulating film 20 and an electrically conductivefilm 21. For example, the insulating film 20 includes a silicon oxide,and the electrically conductive film 21 includes polysilicon. Theinsulating film 20 and the electrically conductive film 21 are providedby the same layers as a gate insulating film and a gate electrode of aMOS (Metal-Oxide-Semiconductor) transistor provided in the semiconductorsubstrate 10 in a region where the pixel P is not provided,respectively.

FIG. 2 illustrates an example of a planar configuration of a diffractivelens DL of the sensor chip 1. The stacked body of the insulating film 20and the electrically conductive film 21 provides the secondconcave-convex section 10D having concavities and convexities providedconcentrically and periodically. The second concave-convex section 10Dcorresponds to one specific example of a “second concave-convex section”of the present disclosure. The second concave-convex section 10D servesas the diffractive lens DL. The diffractive lens DL is an optical memberthat diffracts light to achieve the same working as a lens. Thediffractive lens DL is configured to include fine concavities andconvexities having a size of about that of a wavelength of light andprovided concentrically and periodically.

As illustrated in FIG. 1, a sidewall insulating film 22 is provided insuch a manner as to cover the side wall of the electrically conductivefilm 21 and the surface 10C of the semiconductor substrate 10. Forexample, the sidewall insulating film 22 includes a silicon nitride. Apassivation insulating film 23 is provided in such a manner as to coverthe electrically conductive film 21 and the sidewall insulating film 22.For example, the passivation insulating film 23 includes a siliconoxide.

A wiring layer 26 is provided in such a manner as to cover thepassivation insulating film 23. The wiring layer 26 includes two or morestacked wiring lines embedded in an insulating film 24. The two or morewiring lines include, for example, a first wiring line 25B, a secondwiring line 25D, and a third wiring line 25F. Note that, although FIG. 1illustrates an example including three layers of the stacked wiringlines, the number of layers of the stacked wiring lines is notparticularly limited. The two or more wiring lines are coupled by acontact layer 25A, a first vertical coupling layer 25C, and a secondvertical coupling layer 25E. The first wiring line 25B, the secondwiring line 25D, the third wiring line 25F, the contact layer 25A, thefirst vertical coupling layer 25C, and the second vertical couplinglayer 25E each include, for example, a metal film of copper or the like.The insulating film 24 includes, for example, a silicon oxide. Althoughthe insulating film 24 is illustrated as a single layer in the drawing,it is a stacked body of insulating films corresponding to the respectivelayers of the two or more wiring lines. The contact layer 25A isprovided in such a manner as to run through the sidewall insulating film22 and the passivation insulating film 23 and couple the anode 13 or thecathode 16 to the first wiring line 25B. The two or more wiring linesembedded in the wiring layer 26 are configured to be able to applyrespective predetermined biases to the anode 13 and the cathode 16. Apart, of the first wiring line 25B, opposing the SPAD 2 serves as thelight reflection film LR. The light reflection film LR is configured toreflect light, which has passed through the SPAD 2 and reached thesurface 10C side of the semiconductor substrate 10, back toward the SPAD2. The third wiring line 25F is exposed from the insulating film 24 andserves as a terminal for external coupling.

The first concave-convex section 10B is provided on the back surface(the light entering surface 10A of the SPAD 2) of the semiconductorsubstrate 10. The first concave-convex section 10B corresponds to onespecific example of a “first concave-convex section” of the presentdisclosure. The first concave-convex section 10B includes, for example,quadrangular pyramidal depressions (inverted pyramidal shapes) arrangedin an array. The first concave-convex section 10B diffuses lightentering the SPAD 2 by diffracting and scattering it. By diffusingentering light L, it is possible to increase an optical path length inthe SPAD 2 to thereby improve PDE. The first concave-convex section 10Bis formed, for example, by performing an etching process on the lightentering surface 10A of the semiconductor substrate 10.

An inter-pixel light blocking film 33 is provided on the back surface ofthe semiconductor substrate 10 and is in contact with the pixelseparation film TI. The inter-pixel light blocking film 33 includes, forexample, light blocking metal such as W or Al. The inter-pixel lightblocking film 33 is configured to help to prevent light that hasobliquely entered the light entering surface 10A from failing to enterthe pixel P to enter and entering another pixel P adjacent thereto.

An anti-reflection film 35 is provided in such a manner as to follow theconcavities and convexities of the first concave-convex section 10B andto cover the light entering surface 10A of the SPAD 2. For example, asthe anti-reflection film 35, an insulating thin film having a stackedstructure in which a fixed charge film and an oxide film are stacked andhaving a high dielectric constant (High-k) provided by an ALD (AtomicLayer Deposition) method can be used. For example, the anti-reflectionfilm 35 includes a stacked body of a first anti-reflection film 35A, asecond anti-reflection film 35B, and a third anti-reflection film 35C.The first anti-reflection film 35A, the second anti-reflection film 35B,and the third anti-reflection film 35C each include, for example, ahafnium oxide, an aluminum oxide, a titanium oxide (TiO₂), or a STO(Strontium Titan Oxide). For example, a configuration in which the firstanti-reflection film 35A includes a hafnium oxide, the secondanti-reflection film 35B includes an aluminum oxide, and the thirdanti-reflection film 35C includes a silicon oxide may be used. Thesecond anti-reflection film 35B is provided in the same layer as theinsulating film 31 included in the pixel separation film TI. Inaddition, the third anti-reflection film 35C is provided on the entiresurface to cover the inter-pixel light blocking film 33.

Further, on the back surface of the semiconductor substrate 10, anon-chip lens 34 is provided in an upper layer of the anti-reflectionfilm 35 in such a manner as to cover the light entering surface 10A. Theon-chip lens 34 includes, for example, a light-transmissive materialsuch as a thermoplastic positive photosensitive resin or a siliconnitride. The on-chip lens 34 is configured to collect the entering lightL entering the light entering surface 10A toward the multiplicationregion MR. A protective film 36 is provided on the entire surface in anupper layer of the on-chip lens 34.

[Manufacturing Method]

Next, a process of manufacturing the sensor chip 1 is described. Forexample, the well layer 11, the pinning layer 12, the anode 13, thep-type semiconductor region 14, the n-type semiconductor region 15, thecathode 16, and the p-type semiconductor region 17 are each formed onthe semiconductor substrate 10 by ion implantation. Thereafter, theinsulating film 20 and the electrically conductive film 21 are formed onthe surface 10C of the semiconductor substrate 10, for example, by a CVD(Chemical Vapor Deposition) method, which are etched into a concentricshape to form the second concave-convex section 10D (the diffractivelens DL). Next, the sidewall insulating film 22 and the passivationinsulating film 23 are formed. Thereafter, formation of an insulatingfilm and formation of an electrically conductive film are repeated toform the wiring layer 26. Next, on the back surface of the semiconductorsubstrate 10, polishing of the semiconductor substrate 10 (formation ofthe light entering surface 10A), formation of the pixel separation filmTI, formation of the first concave-convex section 10B, formation of theanti-reflection film 35, formation of the inter-pixel light blockingfilm 33, formation of the on-chip lens 34, and formation of theprotective film 36 are performed. Thus, the sensor chip 1 ismanufactured. [Operation]

In the sensor chip 1, in the SPAD 2 of each pixel P, a high negativevoltage is applied to the anode 13, which by a predetermined reversevoltage is applied to the p-n junction. This causes the depletion layerto spread from the p-n junction of the p-type semiconductor region 14and the n-type semiconductor region 15, thereby providing a highelectric-field region. The obtained high electric-field region providesthe multiplication region MR that allows for avalanche multiplication ofcarriers. The multiplication region MR multiplies carriers generatedfrom a single photon entering from the light entering surface 10A togenerate multiplied signal charge. The obtained signal charge isextracted from the SPAD 2 and subjected to a signal process by thesignal processing circuit.

The sensor chip 1 is usable as a distance measurement sensor based on aToF (Time of Flight) method. In the ToF method, a signal delay timebetween a signal based on the signal charge and a reference signal isconverted into a distance to a measurement target. The signal processingcircuit calculates, for example, the signal delay time from the signalbased on the signal charge obtained from the SPAD 2 of each pixel P andthe reference signal. The obtained signal delay time is converted into adistance. Thus, the distance to the measurement target is measured.

Workings and Effects

The sensor chip 1 of the present embodiment includes the diffractivelens DL provided between the SPAD 2 and the light reflection film LR,and is able to collect light that has entered from the light enteringsurface 10A, passed through the SPAD 2 without being photoelectricallyconverted, and reached the surface 10C side of the semiconductorsubstrate 10, toward the light reflection film LR by the diffractivelens DL.

The light reflection film LR is adapted to reflect, in a directiontoward the SPAD 2, light that has passed through the SPAD 2 withoutbeing photoelectrically converted and reached the surface 10C side ofthe semiconductor substrate 10. In a case where the diffractive lens DLis not provided, the light reaching the surface 10C side of thesemiconductor substrate 10 does not always hit the light reflection filmLR, and sometimes escapes from the gap of the light reflection film LRto the outside of the pixel P. This leads to decrease in PDE. Further,entry of the light escaped from the pixel P into another pixel Psometimes has led to occurrence of crosstalk.

The sensor chip 1 of the present embodiment is provided with thediffractive lens DL as described above. Therefore, it is possible tocollect the light reaching the surface 10C side of the semiconductorsubstrate 10 toward the light reflection film LR. This makes it possibleto increase light reflected by the light reflection film LR andreturning toward the SPAD 2. The returning of the light toward the SPAD2 increases an opportunity to be photoelectrically converted to therebymake a contribution to PDE. This makes it possible to improve PDE.Further, escape of the light to the outside of the pixel P issuppressed. It is thus possible to suppress crosstalk.

In particular, in a case where the first concave-convex section 10B isprovided on the light entering surface 10A, the light entering the SPAD2 is diffused by the first concave-convex section 10B, making itpossible to increase the optical path length in the SPAD 2 to therebyimprove PDE. Meanwhile, on the surface 10C side of the semiconductorsubstrate 10, increase of light not hitting the light reflection film LRhas sometimes led to decrease in PDE. In the sensor chip 1, the firstconcave-convex section 10B is provided on the light entering surface 10Ato improve PDE. Further, on the surface 10C side of the semiconductorsubstrate 10, light is collected toward the light reflection film LR toincrease the light reflected toward the SPAD 2. This also makes itpossible to improve PDE.

As described above, in the sensor chip 1 of the present embodiment, itis possible to improve PDE in the pixel. Furthermore, escape of thelight to the outside of the pixel P is suppressed, making it possible tosuppress crosstalk.

2. MODIFICATIONS

In the following, modifications of the sensor chip 1 according to theabove-described embodiment are described. Note that, in the followingmodifications, the same reference numerals are assigned to theconfigurations common to those in the above-described embodiment.

Modification A

In the above-described sensor chip 1, the second concave-convex section10D (the diffractive lens DL) has a configuration including the stackedbody of the insulating film 20 and the electrically conductive film 21.However, the present disclosure is not limited thereto. The secondconcave-convex section 10D (the diffractive lens DL) may have aconfiguration including an insulating film 27B buried in a groove 27Aprovided on a surface (the surface 10C of the semiconductor substrate10), of the SPAD 2, on an opposite side to the light entering surface10A.

FIG. 3 illustrates an example of a cross-sectional configuration of thepixel P of a sensor chip 1A as Modification A. The groove 27A isprovided on the surface (the surface 10C of the semiconductor substrate10), of the SPAD 2, on the opposite side to the light entering surface10A. The insulating film 27B is buried in the groove 27A. For example,the insulating film 27B includes a silicon oxide. The insulating film27B includes concavities and convexities that are providedconcentrically and periodically to provide the second concave-convexsections 10D. The second concave-convex section 10D functions as adiffractive lens DLA. The insulating film 27B buried in the groove 27Ais provided by the same layer as an STI (Shallow Trench Isolation)device separation film provided in the semiconductor substrate 10 in aregion where the pixel P is not provided. Except for the above, it has aconfiguration similar to that of the sensor chip 1.

In the pixel P of the sensor chip 1A, as with the sensor chip 1, lightthat has passed through the SPAD 2 and reached the surface 10C side ofthe semiconductor substrate 10 is collected by the diffractive lens DLon the light reflection film LR and is reflected by the light reflectionfilm LR toward the SPAD 2. It is thereby possible to improve PDE.Furthermore, escape of the light to the outside of the pixel P issuppressed, making it possible to suppress crosstalk. Further, it ispossible to achieve the diffractive lens DL without the sidewall.

Modification B

In the above-described sensor chip 1, the second concave-convex section10D (the diffractive lens DL) has a configuration including the stackedbody of the insulating film 20 and the electrically conductive film 21.However, the present disclosure is not limited thereto. The secondconcave-convex section 10D (the diffractive lens DL) may have aconfiguration including an electrically conductive film 28 provided on asurface (the surface 10C of the semiconductor substrate 10), of the SPAD2, on the opposite side to the light entering surface 10A.

FIG. 4 illustrates an example of a cross-sectional configuration of thepixel P of a sensor chip 1B as Modification B. The electricallyconductive film 28 is provided on the surface (the surface 10C of thesemiconductor substrate 10), of the SPAD 2, on the opposite side to thelight entering surface 10A with the sidewall insulating film 22 and thepassivation insulating film 23 therebetween. The sidewall insulatingfilm 22 is the same layer as the sidewall insulating film provided onthe sidewall of the gate electrode of the transistor in an unillustratedregion of the semiconductor substrate 10. For example, the electricallyconductive film 28 includes polysilicon. The electrically conductivefilm 28 includes concavities and convexities that are providedconcentrically and periodically to provide the second concave-convexsection 10D. The second concave-convex section 10D functions as adiffractive lens DLB. The electrically conductive film 28 is provided bythe same layer as a film provided as a wiring line in a region where thepixel P is not provided. Except for the above, it has a configurationsimilar to that of the sensor chip 1.

In the pixel P of the sensor chip 1B, as with the sensor chip 1, lightthat has passed through the SPAD 2 and reached the surface 10C side ofthe semiconductor substrate 10 is collected by the diffractive lens DLBon the light reflection film LR and is reflected by the light reflectionfilm LR toward the SPAD 2. It is thereby possible to improve PDE.Furthermore, escape of the light to the outside of the pixel P issuppressed, making it possible to suppress crosstalk. Further, it ispossible to achieve the diffractive lens DL without the sidewall.

The film included in the second concave-convex section 10D is notlimited to the electrically conductive film 28. It is possible to obtaineffects similar to those described above also in a case where the filmincluded in the second concave-convex section 10D includes an insulatingfilm of a silicon oxide, a silicon nitride, or the like. In addition,the electrically conductive film 28 or an insulating film included inthe second concave-convex section 10D may be a multi-layered film.

Modification C

The above-described sensor chip 1 has a configuration in which thediffractive lens DL is provided between the SPAD 2 and the lightreflection film LR. However, the present disclosure is not limitedthereto. A configuration in which an inner lens IL is provided insteadof the diffractive lens DL may be provided.

FIG. 5 illustrates an example of a cross-sectional configuration of thepixel P of a sensor chip 1C as Modification C. The inner lens IL isprovided between the SPAD 2 and the light reflection film LR. The innerlens IL includes, for example, a material having a refractive indexhigher than that of a silicon oxide. FIG. 5 illustrates that the innerlens IL has a shape protruding in a direction from the light reflectionfilm LR toward the SPAD 2. However, this is non-limiting. For example,the inner lens IL may have a shape protruding in a direction from theSPAD 2 toward the light reflection film LR. Except for the above, it hasa configuration similar to that of the sensor chip 1.

In the pixel P of the sensor chip 1C, as with the sensor chip 1, lightthat has passed through the SPAD 2 and reached the surface 10C side ofthe semiconductor substrate 10 is collected by the inner lens IL on thelight reflection film LR, and is reflected by the light reflection filmLR toward the SPAD 2. It is thereby possible to improve PDE.Furthermore, escape of the light to the outside of the pixel P issuppressed, making it possible to suppress crosstalk.

Modification D

In the above-described sensor chip 1, the second concave-convex section10D (the diffractive lens DL) has a configuration including the stackedbody of the insulating film 20 and the electrically conductive film 21.However, the present disclosure is not limited thereto. The secondconcave-convex section 10D (the diffractive lens DL) may include anelectrically conductive film in the same layer as one of the layers ofthe two or more wiring lines embedded in the wiring layer 26.

FIG. 6 illustrates an example of a cross-sectional configuration of thepixel P of the sensor chip 1D as Modification D. Two or more stackedwiring lines are embedded in the wiring layer 26. The two or more wiringlayers include, for example, the first wiring line 25B, the secondwiring line 25D, the third wiring line 25F, and a fourth wiring line25H. Note that, although FIG. 6 illustrates an example including thewiring lines of four stacked layers, the number of the stacked layers ofthe wiring lines is not particularly limited. These wiring lines arecoupled by the contact layer 25A, the first vertical coupling layer 25C,the second vertical coupling layer 25E, and a third vertical couplinglayer 25G. The first wiring line 25B, the second wiring line 25D, thethird wiring line 25F, the fourth wiring line 25H, the contact layer25A, the first vertical coupling layer 25C, the second vertical couplinglayer 25E, and the third vertical coupling layer 25G each include, forexample, a metal film of copper or the like. The second concave-convexsection 10D is provided on the electrically conductive film of the samelayer as the first wiring line 25B to provide a diffractive lens DLC.This first wiring line 25B is a layer closest to the SPAD 2 of thestacked wiring lines. Further, a part, of the second wiring line 25D,opposing the SPAD 2 is included in the light reflection film LR. Thethird wiring line 25F is provided inside the insulating film 24. Thefourth wiring line 25H is exposed from the insulating film 24, andserves as a terminal for external coupling. Except for the above, it hasa configuration similar to that of the sensor chip 1.

In the pixel P of the sensor chip 1D, as with the sensor chip 1, lightthat has passed through the SPAD 2 and reached the surface 10C side ofthe semiconductor substrate 10 is collected by the diffractive lens DLCon the light reflection film LR, and is reflected by the lightreflection film LR toward the SPAD 2. It is thereby possible to improvePDE. Furthermore, escape of the light to the outside of the pixel P issuppressed, making it possible to suppress crosstalk. Changing thelayout shape of the two or more wiring lines embedded in the wiringlayer 26 makes it possible to achieve a structure including thediffractive lens DL and the light reflection film LR.

Modification E

The above-described sensor chip 1D has a configuration in which thesecond concave-convex section 10D (the diffractive lens DLC) is providedin the layer (the first wiring line 25B) closest to the SPAD 2 of thestacked wiring lines. However, the present disclosure is not limitedthereto. The contact layer 25A may be provided between each of the firstwiring lines 25B included in the concentric second concave-convexsection 10D and the SPAD 2.

FIG. 7 illustrates an example of a cross-sectional configuration of thepixel P of a sensor chip 1E as Modification E. A configuration of thetwo or more stacked wiring lines embedded in the wiring layer 26 issimilar to that of the sensor chip 1D. In the sensor chip 1E, thecontact layer 25A is provided between each of the first wiring lines 25Bincluded in the concentric second concave-convex section 10D and theSPAD 2.

A planar configuration of the second concave-convex sections 10Dincluding the first wiring lines 25B is similar to that illustrated inFIG. 2, and they are provided concentrically and periodically. FIG. 8illustrates an example of a planar configuration of the contact layers25A of the sensor chip 1E. The contact layer 25A is provided betweeneach of the first wiring lines 25B included in the concentric secondconcave-convex sections 10D and the SPAD 2. The contact layers 25A areprovided, for example, in a dot-shaped layout shape illustrated in FIG.8. The contact layers 25A in the dot shape each overlap any of theconcentric second concave-convex sections 10D. That is, the contactlayers 25A are each provided in such a manner as to be coupled to any ofthe second concave-convex sections 10D. Except for the above, it has aconfiguration similar to that of the sensor chip 1D. Note that thecontact layers 25A are not limited to the dot-shaped layout illustratedin FIG. 8. For example, the contact layers 25A may have a concentriclayout shape as with the second concave-convex sections 10D.Alternatively, they may have a liner layout shape.

In the pixel P of the sensor chip 1E, as with the sensor chip 1D, lightthat has passed through the SPAD 2 and reached the surface 10C side ofthe semiconductor substrate 10 is collected by the diffractive lens DLCon the light reflection film LR and is reflected by the light reflectionfilm LR toward the SPAD 2. It is thereby possible to improve PDE.Furthermore, escape of the light to the outside of the pixel P issuppressed, making it possible to suppress crosstalk. Changing thelayout shape of the two or more wiring lines embedded in the wiringlayer makes it possible to provide the diffractive lens DL and the lightreflection film LR. The contact layers 25A are so provided as to becoupled to the respective concentric first wiring lines 25B. Therefore,it is possible to change the position of the cathode 16 in a range thatallows for coupling to the contact layer 25A. This increases a degree offreedom in design. In a case where the cathode 16 is coupled to thefirst wiring line 25B that is not the outermost one of the concentricfirst wiring lines 25B, the layout shape of the second wiring line 25Dand the wiring lines in its upper layers is selected so as to allow forcoupling to the first wiring line 25B to which the cathode 16 iscoupled. In this case, it is possible to reduce the size of the lightreflection film LR as will be described later in Modification G. It isthereby possible to reduce a pixel capacity.

In the sensor chip 1E, the second concave-convex section 10D includes anelectrically conductive layer in the same layer as the first wiring line25B. However, the second concave-convex section 10D may include anelectrically conductive film in the same layer as the layer (the secondwiring line 25D and the wiring lines in its upper layers) that is notthe layer closest to the SPAD 2 of the wiring lines.

Modification F

The above-described sensor chip 1E has a configuration in which thecathode 16 is provided at a position closer to an end than a middle partof the pixel P. However, the present disclosure is not limited thereto.The cathode 16 may be provided at the middle part of the pixel P in adirection parallel to the light entering surface 10A.

FIG. 9 illustrates an example of a cross-sectional configuration of thepixel P of a sensor chip 1F as Modification F. The second concave-convexsection 10D includes the stacked body of the insulating film 20 and theelectrically conductive film 21. The cathode 16 is provided at themiddle part of the pixel P in the direction parallel to the lightentering surface 10A, and the contact layer 25A and the first wiringline 25B are provided in such a manner as to be coupled to the cathode16. The light reflection film LR includes an electrically conductivefilm of the same layer as the second wiring line 25D. Except for theabove, it has a configuration similar to that of the sensor chip 1E.

In the pixel P of the sensor chip 1F, as with the sensor chip 1E, lightthat has passed through the SPAD 2 and reached the surface 10C side ofthe semiconductor substrate 10 is collected by the diffractive lens DLon the light reflection film LR and is reflected by the light reflectionfilm LR toward the SPAD 2. It is thereby possible to improve PDE.Furthermore, escape of the light to the outside of the pixel P issuppressed, making it possible to suppress crosstalk.

Modification G

The above-described sensor chip 1F has a configuration in which thelight reflection film LR is provided to oppose the substantially entireregion of the pixel P in the direction parallel to the light enteringsurface 10A. However, the present disclosure is not limited thereto. Itmay have a configuration in which the light reflection film LR isprovided to oppose a portion of the pixel P including the middle part inthe direction parallel to the light entering surface 10A.

FIG. 10 illustrates an example of a cross-sectional configuration of thepixel P of a sensor chip 1G as Modification G. The light reflection filmLR includes an electrically conductive layer of the same layer as thesecond wiring line 25D, and is provided to oppose a portion of the pixelP including the middle part in the direction parallel to the lightentering surface 10A. That is, the area extending in the directionparallel to the light entering surface 10A is smaller than that of thelight reflection film LR having the configuration of being provided tooppose the substantially entire region of the pixel as illustrated inFIG. 9. Except for the above, it has a configuration similar to that ofthe sensor chip 1F.

In the pixel P of the sensor chip 1G, as with the sensor chip 1F, lightthat has passed through the SPAD 2 and reached the surface 10C side ofthe semiconductor substrate 10 is collected by the diffractive lens DLon the light reflection film LR and is reflected by the light reflectionfilm LR toward the SPAD 2. It is thereby possible to improve PDE.Furthermore, escape of the light to the outside of the pixel P issuppressed, making it possible to suppress crosstalk. Reducing the sizeof the light reflection film LR makes it possible to reduce a pixelcapacity.

Modification H

In the above-described sensor chip 1G, the two or more wiring linesembedded in the wiring layer 26 are a stacked body of four layer ofwiring lines. However, the present disclosure is not limited thereto.The two or more wiring lines embedded in the wiring layer 26 may includethree or less layers.

FIG. 11 illustrates an example of a cross-sectional configuration of thepixel P of the sensor chip 1H as Modification H. The two or more wiringlines embedded in the wiring layer 26 are a stacked body of three layersincluding the first wiring line 25B, the second wiring line 25D, and thethird wiring line 25F. These wiring lines are coupled by the contactlayer 25A, the first vertical coupling layer 25C, and the secondvertical coupling layer 25E. The light reflection film LR includes anelectrically conductive layer of the same layer as the first wiring line25B, and is provided to oppose a portion of the pixel P including themiddle part in the direction parallel to the light entering surface 10A.Except for the above, it has a configuration similar to that of thesensor chip 1G.

In the pixel P of the sensor chip 1H, as with the sensor chip 1G, lightthat has passed through the SPAD 2 and reached the surface 10C side ofthe semiconductor substrate 10 is collected by the diffractive lens DLon the light reflection film LR and is reflected by the light reflectionfilm LR toward the SPAD 2. It is thereby possible to improve PDE.Furthermore, escape of the light to the outside of the pixel P issuppressed, making it possible to suppress crosstalk. Decrease in thenumber of layers of the wiring lines embedded in the wiring layer 26 inaddition to the reduction of the size of the light reflection film LRmakes it possible to reduce a pixel capacity.

Modification I

In the above-described sensor chip 1, the first concave-convex section10B is provided on the light entering surface 10A of the SPAD 2.However, the present disclosure is not limited thereto. The lightentering surface 10A may be a flat surface.

FIG. 12 illustrates an example of a cross-sectional configuration of thepixel P of a sensor chip 1I as Modification I. The light enteringsurface 10A of the SPAD 2 is a flat surface. The anti-reflection film 35covering the light entering surface 10A is also formed to be flat.Except for the above, it has a configuration similar to that of thesensor chip 1.

In the pixel P of the sensor chip 1I, as with the sensor chip 1, lightthat has passed through the SPAD 2 and reached the surface 10C side ofthe semiconductor substrate 10 is collected by the diffractive lens DLon the light reflection film LR and is reflected by the light reflectionfilm LR toward the SPAD 2. It is thereby possible to improve PDE.Furthermore, escape of the light to the outside of the pixel P issuppressed, making it possible to suppress crosstalk. Althoughscattering of light by the first concave-convex section 10B does notoccur, it is possible to obtain similar effects in terms of contributionto sensitivity by returning, to the SPAD 2 side, the light that haspassed through the SPAD 2 and reached the surface 10C side of thesemiconductor substrate 10.

Modification J

In the above-described sensor chip 1I, the on-chip lens 34 is providedto oppose the light entering surface 10A of the SPAD 2. However, thepresent disclosure is not limited thereto. A configuration without theon-chip lens 34 may be provided.

FIG. 13 illustrates an example of a cross-sectional configuration of thepixel P of a sensor chip 1J as Modification J. The light enteringsurface 10A of the SPAD 2 is a flat surface, and the anti-reflectionfilm 35 provided to cover the light entering surface 10A also has a flatsurface. No on-ship lens 34 is provided on the light entering surface10A. Except for the above, it has a configuration similar to that of thesensor chip 1.

In the pixel P of the sensor chip 1J, as with the sensor chip 1I, lightthat has passed through the SPAD 2 and reached the surface 10C side ofthe semiconductor substrate 10 is collected by the diffractive lens DLon the light reflection film LR, and is reflected by the lightreflection film LR toward the SPAD 2. It is thereby possible to improvePDE. Furthermore, escape of the light to the outside of the pixel P issuppressed, making it possible to suppress crosstalk. Althoughscattering of light by the first concave-convex section 10B does notoccur, it is possible to obtain similar effects in terms of contributionto sensitivity by returning, to the SPAD 2 side, the light that haspassed through the SPAD 2 and reached the surface 10C side of thesemiconductor substrate 10. In particular, because no on-chip lens 34 isprovided, the amount of light passing through the SPAD 2 and reachingthe surface 10C side of the semiconductor substrate 10 increases. Thisenhances the effect of improving PDE by collecting the light on thelight reflection film LR by the diffractive lens DL and reflecting ittoward the SPAD 2 by the light reflection film LR.

3. APPLICATION EXAMPLE

The sensor chips 1 and 1A to 1J described above (represented by thesensor chip 1) are applicable to, for example, various electronicapparatuses including a camera such as a digital still camera or adigital video camera, a mobile phone having an imaging function, or anyother device having an imaging function.

FIG. 14 is a block diagram illustrating an example of a schematicconfiguration of an electronic apparatus including the sensor chip 1according to any of the embodiment and the modifications thereofdescribed above.

An electronic apparatus 201 illustrated in FIG. 14 includes an opticalsystem 202, a shutter device 203, the sensor chip 1, a drive circuit205, a signal processing circuit 206, a monitor 207, and a memory 208,and is able to perform imaging of a still image and a moving image.

The optical system 202 includes one or more lenses. The optical system202 guides light (entering light) from a subject to the sensor chip 1 toform an image on a light receiving surface of the sensor chip 1.

The shutter device 203 is disposed between the optical system 202 andthe sensor chip 1. The shutter device 203 controls a period of applyinglight to the sensor chip 1 and a period of blocking the light inaccordance with a control by the drive circuit 205.

The sensor chip 1 includes a package including the sensor chip describedabove. The sensor chip 1 generates signal charge in accordance withlight formed into an image on the light receiving surface via theoptical system 202 and the shutter device 203. The signal chargegenerated in the sensor chip 1 is supplied to the signal processingcircuit 206.

The signal processing circuit 206 performs various signal processes onthe signal charge supplied from the sensor chip 1. An image (image data)obtained as a result of the signal process performed by the signalprocessing circuit 206 is supplied to the monitor 207 to be displayed,or is supplied to the memory 208 to be stored (recorded).

Application of the sensor chip 1 allows the electronic apparatus 201configured as described above to improve PDE and to thereby obtain ahigh-definition imaging image.

4. PRACTICAL APPLICATION EXAMPLE

The technology (the present technology) according to the presentdisclosure is applicable to a variety of products. For example, thetechnology according to the present disclosure may be achieved as adevice mounted on any type of mobile body such as an automobile, anelectric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, apersonal mobility, an airplane, a drone, a vessel, or a robot.

FIG. 15 is a block diagram depicting an example of schematicconfiguration of a vehicle control system as an example of a mobile bodycontrol system to which the technology according to an embodiment of thepresent disclosure can be applied.

The vehicle control system 12000 includes a plurality of electroniccontrol units connected to each other via a communication network 12001.In the example depicted in FIG. 15, the vehicle control system 12000includes a driving system control unit 12010, a body system control unit12020, an outside-vehicle information detecting unit 12030, anin-vehicle information detecting unit 12040, and an integrated controlunit 12050. In addition, a microcomputer 12051, a sound/image outputsection 12052, and a vehicle-mounted network interface (I/F) 12053 areillustrated as a functional configuration of the integrated control unit12050.

The driving system control unit 12010 controls the operation of devicesrelated to the driving system of the vehicle in accordance with variouskinds of programs. For example, the driving system control unit 12010functions as a control device for a driving force generating device forgenerating the driving force of the vehicle, such as an internalcombustion engine, a driving motor, or the like, a driving forcetransmitting mechanism for transmitting the driving force to wheels, asteering mechanism for adjusting the steering angle of the vehicle, abraking device for generating the braking force of the vehicle, and thelike.

The body system control unit 12020 controls the operation of variouskinds of devices provided to a vehicle body in accordance with variouskinds of programs. For example, the body system control unit 12020functions as a control device for a keyless entry system, a smart keysystem, a power window device, or various kinds of lamps such as aheadlamp, a backup lamp, a brake lamp, a turn signal, a fog lamp, or thelike. In this case, radio waves transmitted from a mobile device as analternative to a key or signals of various kinds of switches can beinput to the body system control unit 12020. The body system controlunit 12020 receives these input radio waves or signals, and controls adoor lock device, the power window device, the lamps, or the like of thevehicle.

The outside-vehicle information detecting unit 12030 detects informationabout the outside of the vehicle including the vehicle control system12000. For example, the outside-vehicle information detecting unit 12030is connected with an imaging section 12031. The outside-vehicleinformation detecting unit 12030 makes the imaging section 12031 imagean image of the outside of the vehicle, and receives the imaged image.On the basis of the received image, the outside-vehicle informationdetecting unit 12030 may perform processing of detecting an object suchas a human, a vehicle, an obstacle, a sign, a character on a roadsurface, or the like, or processing of detecting a distance thereto.

The imaging section 12031 is an optical sensor that receives light, andwhich outputs an electric signal corresponding to a received lightamount of the light. The imaging section 12031 can output the electricsignal as an image, or can output the electric signal as informationabout a measured distance. In addition, the light received by theimaging section 12031 may be visible light, or may be invisible lightsuch as infrared rays or the like.

The in-vehicle information detecting unit 12040 detects informationabout the inside of the vehicle. The in-vehicle information detectingunit 12040 is, for example, connected with a driver state detectingsection 12041 that detects the state of a driver. The driver statedetecting section 12041, for example, includes a camera that images thedriver. On the basis of detection information input from the driverstate detecting section 12041, the in-vehicle information detecting unit12040 may calculate a degree of fatigue of the driver or a degree ofconcentration of the driver, or may determine whether the driver isdozing.

The microcomputer 12051 can calculate a control target value for thedriving force generating device, the steering mechanism, or the brakingdevice on the basis of the information about the inside or outside ofthe vehicle which information is obtained by the outside-vehicleinformation detecting unit 12030 or the in-vehicle information detectingunit 12040, and output a control command to the driving system controlunit 12010. For example, the microcomputer 12051 can perform cooperativecontrol intended to implement functions of an advanced driver assistancesystem (ADAS) which functions include collision avoidance or shockmitigation for the vehicle, following driving based on a followingdistance, vehicle speed maintaining driving, a warning of collision ofthe vehicle, a warning of deviation of the vehicle from a lane, or thelike.

In addition, the microcomputer 12051 can perform cooperative controlintended for automatic driving, which makes the vehicle to travelautonomously without depending on the operation of the driver, or thelike, by controlling the driving force generating device, the steeringmechanism, the braking device, or the like on the basis of theinformation about the outside or inside of the vehicle which informationis obtained by the outside-vehicle information detecting unit 12030 orthe in-vehicle information detecting unit 12040.

In addition, the microcomputer 12051 can output a control command to thebody system control unit 12020 on the basis of the information about theoutside of the vehicle which information is obtained by theoutside-vehicle information detecting unit 12030. For example, themicrocomputer 12051 can perform cooperative control intended to preventa glare by controlling the headlamp so as to change from a high beam toa low beam, for example, in accordance with the position of a precedingvehicle or an oncoming vehicle detected by the outside-vehicleinformation detecting unit 12030.

The sound/image output section 12052 transmits an output signal of atleast one of a sound and an image to an output device capable ofvisually or auditorily notifying information to an occupant of thevehicle or the outside of the vehicle. In the example of FIG. 15, anaudio speaker 12061, a display section 12062, and an instrument panel12063 are illustrated as the output device. The display section 12062may, for example, include at least one of an on-board display and ahead-up display.

FIG. 16 is a diagram depicting an example of the installation positionof the imaging section 12031.

In FIG. 16, the imaging section 12031 includes imaging sections 12101,12102, 12103, 12104, and 12105.

The imaging sections 12101, 12102, 12103, 12104, and 12105 are, forexample, disposed at positions on a front nose, sideview mirrors, a rearbumper, and a back door of the vehicle 12100 as well as a position on anupper portion of a windshield within the interior of the vehicle. Theimaging section 12101 provided to the front nose and the imaging section12105 provided to the upper portion of the windshield within theinterior of the vehicle obtain mainly an image of the front of thevehicle 12100. The imaging sections 12102 and 12103 provided to thesideview mirrors obtain mainly an image of the sides of the vehicle12100. The imaging section 12104 provided to the rear bumper or the backdoor obtains mainly an image of the rear of the vehicle 12100. Theimaging section 12105 provided to the upper portion of the windshieldwithin the interior of the vehicle is used mainly to detect a precedingvehicle, a pedestrian, an obstacle, a signal, a traffic sign, a lane, orthe like.

Incidentally, FIG. 16 depicts an example of photographing ranges of theimaging sections 12101 to 12104. An imaging range 12111 represents theimaging range of the imaging section 12101 provided to the front nose.Imaging ranges 12112 and 12113 respectively represent the imaging rangesof the imaging sections 12102 and 12103 provided to the sideviewmirrors. An imaging range 12114 represents the imaging range of theimaging section 12104 provided to the rear bumper or the back door. Abird's-eye image of the vehicle 12100 as viewed from above is obtainedby superimposing image data imaged by the imaging sections 12101 to12104, for example.

At least one of the imaging sections 12101 to 12104 may have a functionof obtaining distance information. For example, at least one of theimaging sections 12101 to 12104 may be a stereo camera constituted of aplurality of imaging elements, or may be an imaging element havingpixels for phase difference detection.

For example, the microcomputer 12051 can determine a distance to eachthree-dimensional object within the imaging ranges 12111 to 12114 and atemporal change in the distance (relative speed with respect to thevehicle 12100) on the basis of the distance information obtained fromthe imaging sections 12101 to 12104, and thereby extract, as a precedingvehicle, a nearest three-dimensional object in particular that ispresent on a traveling path of the vehicle 12100 and which travels insubstantially the same direction as the vehicle 12100 at a predeterminedspeed (for example, equal to or more than 0 km/hour). Further, themicrocomputer 12051 can set a following distance to be maintained infront of a preceding vehicle in advance, and perform automatic brakecontrol (including following stop control), automatic accelerationcontrol (including following start control), or the like. It is thuspossible to perform cooperative control intended for automatic drivingthat makes the vehicle travel autonomously without depending on theoperation of the driver or the like.

For example, the microcomputer 12051 can classify three-dimensionalobject data on three-dimensional objects into three-dimensional objectdata of a two-wheeled vehicle, a standard-sized vehicle, a large-sizedvehicle, a pedestrian, a utility pole, and other three-dimensionalobjects on the basis of the distance information obtained from theimaging sections 12101 to 12104, extract the classifiedthree-dimensional object data, and use the extracted three-dimensionalobject data for automatic avoidance of an obstacle. For example, themicrocomputer 12051 identifies obstacles around the vehicle 12100 asobstacles that the driver of the vehicle 12100 can recognize visuallyand obstacles that are difficult for the driver of the vehicle 12100 torecognize visually. Then, the microcomputer 12051 determines a collisionrisk indicating a risk of collision with each obstacle. In a situationin which the collision risk is equal to or higher than a set value andthere is thus a possibility of collision, the microcomputer 12051outputs a warning to the driver via the audio speaker 12061 or thedisplay section 12062, and performs forced deceleration or avoidancesteering via the driving system control unit 12010. The microcomputer12051 can thereby assist in driving to avoid collision.

At least one of the imaging sections 12101 to 12104 may be an infraredcamera that detects infrared rays. The microcomputer 12051 can, forexample, recognize a pedestrian by determining whether or not there is apedestrian in imaged images of the imaging sections 12101 to 12104. Suchrecognition of a pedestrian is, for example, performed by a procedure ofextracting characteristic points in the imaged images of the imagingsections 12101 to 12104 as infrared cameras and a procedure ofdetermining whether or not it is the pedestrian by performing patternmatching processing on a series of characteristic points representingthe contour of the object. When the microcomputer 12051 determines thatthere is a pedestrian in the imaged images of the imaging sections 12101to 12104, and thus recognizes the pedestrian, the sound/image outputsection 12052 controls the display section 12062 so that a squarecontour line for emphasis is displayed so as to be superimposed on therecognized pedestrian. The sound/image output section 12052 may alsocontrol the display section 12062 so that an icon or the likerepresenting the pedestrian is displayed at a desired position.

The above has described the example of the mobile body control system towhich the technology according to the present disclosure is applicable.The technology according to the present disclosure is applicable to theimaging section 12031 among the above-described components.Specifically, the sensor chip 1 according to any of the embodiment andthe modifications thereof described above is applicable to the imagingsection 12031. The application of the technology according to thepresent disclosure to the imaging section 12031 makes it possible toimprove PDE and to thereby obtain a high-definition imaging image. It istherefore possible to perform a highly accurate control utilizing animaging image in the mobile body control system.

5. OTHER MODIFICATIONS

The present disclosure has been described above with reference to theembodiment, the modifications A to J thereof, the application example,and the practical application example. However, the present disclosureis not limited to the embodiment and the like described above, and ismodifiable in a variety of ways.

The sensor chip of any of the embodiment and the modifications thereofdescribed above is applicable to a distance measurement apparatus thatcalculates a distance from an output signal of the sensor chip to ameasurement target. In this case, the distance measurement apparatusincludes a signal processing circuit that calculates the distance fromthe output signal of the sensor chip to the measurement target.

Further, in the sensor chip of any of the embodiment and themodifications described above, a light collection section such as adiffractive lens or an inner lens does not have to be provided outsidean effective pixel region, for example, in an ineffective pixel in whichlight is blocked by a light blocking film or in a pixel peripheralsection. In the case of providing a pixel array, the number of pixels isnot particularly limited. Further, the embodiment and the modificationsA to J thereof can be appropriately combined.

Further, the SPAD 2 of each of the pixels P of the embodiment and themodifications A to J thereof may have a configuration in which then-type impurity region and the p-type impurity region are replaced witheach other. In this case, the n-type impurity region is provided betweenthe side surface of the well layer 11 and the pixel separation film TI,and a cathode is provided at its end. Further, an n-type impurity regionand a p-type impurity region providing a p-n junction are providedinside the well layer 11, and an anode is provided so as to be coupledto this p-type impurity region. Driving of the SPAD having such aconfiguration is performed by applying a high negative voltage to theanode 13 and thereby applying a predetermined reverse voltage to the p-njunction.

It is to be noted that the effects described herein are merelyillustrative. The effects of the present disclosure are not limited tothe effects described herein. The present disclosure may have effectsother than the effects described herein.

Note that the present technology may have the following configurations.According to the present technology having the following configurations,it is possible to improve PDE.

(1)

A sensor chip including

a pixel including

-   -   a photoelectric converter that includes a light entering surface        which light enters and a multiplication region in which        avalanche multiplication of carriers is caused by a high        electric-field region,    -   a light reflector that is provided to oppose a surface, of the        photoelectric converter, on an opposite side to the light        entering surface, and    -   a light collector that is provided between the photoelectric        converter and the light reflector.        (2)

The sensor chip according to (1) described above, in which the lightcollector collects, toward the light reflector, the light passingthrough the photoelectric converter.

(3)

The sensor chip according to (1) or (2) described above, in which thelight entering surface is provided with a first concave-convex sectionthat diffuses the light.

(4)

The sensor chip according to any one of (1) to (3) described above,further including an on-chip lens that is provided to oppose the lightentering surface.

(5)

The sensor chip according to any one of (1) to (4) described above, inwhich the light collector includes a diffractive lens.

(6)

The sensor chip according to (5) described above, in which thediffractive lens includes second concave-convex sections that areprovided concentrically and periodically.

(7)

The sensor chip according to (6) described above, in which the secondconcave-convex section includes an electrically conductive film.

(8)

The sensor chip according to (6) described above, in which the secondconcave-convex section includes a stacked body of an insulating film andan electrically conductive film.

(9)

The sensor chip according to (6) described above, in which the secondconcave-convex section includes an insulating film.

(10)

The sensor chip according to (9) described above, in which theinsulating film is buried in a groove provided on the surface, of thephotoelectric converter, on the opposite side to the light enteringsurface.

(11)

The sensor chip according to (6) described above, in which

a wiring layer is provided on the surface, of the photoelectricconverter, on the opposite side to the light entering surface, thewiring layer including two or more stacked wiring lines that areembedded in an insulating film, and

the second concave-convex section includes an electrically conductivefilm in the same layer as one of the two or more wiring lines.

(12)

The sensor chip according to (11) described above, in which a contactsection is provided between each of the electrically conductive filmsincluded in the second concave-convex sections provided concentricallyand the photoelectric converter.

(13)

The sensor chip according to (11) or (12) described above, in which thesecond concave-convex section includes an electrically conductive filmin the same layer as a layer, of the two or more wiring lines, closestto the photoelectric converter.

(14)

The sensor chip according to (11) or (12) described above, in which thesecond concave-convex section includes an electrically conductive filmin the same layer as a layer that is other than a layer, of the two ormore wiring lines, closest to the photoelectric converter.

(15)

The sensor chip according to (6) described above, in which

a wiring layer is provided on the surface, of the photoelectricconverter, on the opposite side to the light entering surface, thewiring layer including two or more stacked wiring lines that areembedded in an insulating film, and

the two or more wiring lines are provided to be coupled to a cathode ofthe photoelectric converter at a middle part of the pixel in a directionparallel to the light entering surface.

(16)

The sensor chip according to any one of (1) to (15) described above, inwhich the light reflector is provided to oppose a portion of the pixelincluding a middle part of the pixel in a direction parallel to thelight entering surface.

(17)

The sensor chip according to any one of (1) to (4) described above, inwhich the light collector includes an inner lens.

(18)

An electronic apparatus including:

an optical system;

a sensor chip; and

a signal processing circuit, in which

the sensor chip includes a pixel including

-   -   a photoelectric converter that includes a light entering surface        which light enters and a multiplication region in which        avalanche multiplication of carriers is caused by a high        electric-field region,    -   a light reflector that is provided to oppose a surface, of the        photoelectric converter, on an opposite side to the light        entering surface, and    -   a light collector that is provided between the photoelectric        converter and the light reflector.        (19)

A distance measurement apparatus including:

an optical system;

a sensor chip; and

a signal processing circuit that calculates a distance from an outputsignal of the sensor chip to a measurement target, in which

the sensor chip includes a pixel including

-   -   a photoelectric converter that includes a light entering surface        which light enters and a multiplication region in which        avalanche multiplication of carriers is caused by a high        electric-field region,    -   a light reflector that is provided to oppose a surface, of the        photoelectric converter, on an opposite side to the light        entering surface, and    -   a light collector that is provided between the photoelectric        converter and the light reflector.

This application claims the priority on the basis of Japanese PatentApplication No. 2019-050885 filed on Mar. 19, 2019 with Japan PatentOffice, the entire contents of which are incorporated in thisapplication by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations, and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

1. A sensor chip comprising a pixel including a photoelectric converterthat includes a light entering surface which light enters and amultiplication region in which avalanche multiplication of carriers iscaused by a high electric-field region, a light reflector that isprovided to oppose a surface, of the photoelectric converter, on anopposite side to the light entering surface, and a light collector thatis provided between the photoelectric converter and the light reflector.2. The sensor chip according to claim 1, wherein the light collectorcollects, toward the light reflector, the light passing through thephotoelectric converter.
 3. The sensor chip according to claim 1,wherein the light entering surface is provided with a firstconcave-convex section that diffuses the light.
 4. The sensor chipaccording to claim 1, further comprising an on-chip lens that isprovided to oppose the light entering surface.
 5. The sensor chipaccording to claim 1, wherein the light collector includes a diffractivelens.
 6. The sensor chip according to claim 5, wherein the diffractivelens includes second concave-convex sections that are providedconcentrically and periodically.
 7. The sensor chip according to claim6, wherein the second concave-convex section includes an electricallyconductive film.
 8. The sensor chip according to claim 6, wherein thesecond concave-convex section includes a stacked body of an insulatingfilm and an electrically conductive film.
 9. The sensor chip accordingto claim 6, wherein the second concave-convex section includes aninsulating film.
 10. The sensor chip according to claim 9, wherein theinsulating film is buried in a groove provided on the surface, of thephotoelectric converter, on the opposite side to the light enteringsurface.
 11. The sensor chip according to claim 6, wherein a wiringlayer is provided on the surface, of the photoelectric converter, on theopposite side to the light entering surface, the wiring layer includingtwo or more stacked wiring lines that are embedded in an insulatingfilm, and the second concave-convex section includes an electricallyconductive film in same layer as one of the two or more wiring lines.12. The sensor chip according to claim 11, wherein a contact section isprovided between each of the electrically conductive films included inthe second concave-convex sections provided concentrically and thephotoelectric converter.
 13. The sensor chip according to claim 11,wherein the second concave-convex section includes an electricallyconductive film in same layer as a layer, of the two or more wiringlines, closest to the photoelectric converter.
 14. The sensor chipaccording to claim 11, wherein the second concave-convex sectionincludes an electrically conductive film in same layer as a layer thatis other than a layer, of the two or more wiring lines, closest to thephotoelectric converter.
 15. The sensor chip according to claim 6,wherein a wiring layer is provided on the surface, of the photoelectricconverter, on the opposite side to the light entering surface, thewiring layer including two or more stacked wiring lines that areembedded in an insulating film, and the two or more wiring lines areprovided to be coupled to a cathode of the photoelectric converter at amiddle part of the pixel in a direction parallel to the light enteringsurface.
 16. The sensor chip according to claim 1, wherein the lightreflector is provided to oppose a portion of the pixel including amiddle part of the pixel in a direction parallel to the light enteringsurface.
 17. The sensor chip according to claim 1, wherein the lightcollector includes an inner lens.
 18. An electronic apparatuscomprising: an optical system; a sensor chip; and a signal processingcircuit, wherein the sensor chip includes a pixel including aphotoelectric converter that includes a light entering surface whichlight enters and a multiplication region in which avalanchemultiplication of carriers is caused by a high electric-field region, alight reflector that is provided to oppose a surface, of thephotoelectric converter, on an opposite side to the light enteringsurface, and a light collector that is provided between thephotoelectric converter and the light reflector.
 19. A distancemeasurement apparatus comprising: an optical system; a sensor chip; anda signal processing circuit that calculates a distance from an outputsignal of the sensor chip to a measurement target, wherein the sensorchip includes a pixel including a photoelectric converter that includesa light entering surface which light enters and a multiplication regionin which avalanche multiplication of carriers is caused by a highelectric-field region, a light reflector that is provided to oppose asurface, of the photoelectric converter, on an opposite side to thelight entering surface, and a light collector that is provided betweenthe photoelectric converter and the light reflector.